This invention relates to a carafe/pitcher water filtration system. More particularly, the instant invention is directed to a batch treatment and filtration device where water is filtered, treated and stored in a container. The treated water is poured from a spigot of the water container which functions as a self-contained water treatment system. These self-contained systems typically have upper and lower chambers separated by a filter cartridge. The water treatment process relies on gravity to force water through the filter cartridge to remove harmful contaminants from the water. The upper chamber receives untreated water to be filtered. The lower chamber receives the filtered water, which is forced through the filter cartridge by gravity.
The presence of unwanted and potentially harmful contaminants in drinking water are a cause for health concern. This concern causes a desire for water treatment devices suitable for use in the home and as portable instruments for water treatment. As a result, many water treatment devices and methods have been developed to remove contaminants or otherwise treat the water to obtain a suitable drinking water.
Some of these water treatment devices and methods utilize treatment materials, which, of their own nature, can be distasteful to consumers of the treated water. For example, municipal water treatment facilities use chlorine as an active agent to remove bacterial contaminants but the odor and taste of the treated water can be offensive to the consumers. It is known to use activated carbon to treat water to remove the offensive odor and taste of chlorine-treated water but flow rate of water through the activated carbon can be hampered.
In addition to chemical and particulate contaminants, several types of harmful contaminants in drinking water are a cause for health concern. Even municipal water treatment fails to adequately remove all of the hazardous contaminates. Most municipal system use chlorine as disinfectant to remove bacteria. It is known that excess chlorine normally used by the municipality is in itself a source to create harmful chemicals commonly known as disinfectant by products, (DBP). These DBP, along with herbicides and pesticides, often present and known as volatile organic chemicals (VOC) are harmful chemicals in the water system. Besides these volatile organic chemical contaminants, biological contaminants including protozoan cysts as Giarida, lamibial and Cryptosporidium, excreted by animals, are present in certain waters.
Cysts are not easily removed by conventional oxidizing agents. Common methods of removing cysts are to trap them in a filter that has porosity less than 2 microns. Such filters with pore sizes less than 2 microns typically are used in water purifier systems that provide high water line pressure.
Gravity filtration is one of the oldest ways of filtering water. Starting from a simple filter cloth to remove suspended impurities to carbon granules along with certain ion exchange media to remove chlorine and certain heavy metals, gravity filtration systems have upper and lower chambers separated by filter cartridge. The system relies on gravity force of the untreated water in the upper chamber to force the water through the cartridge and into the lower chamber thereby producing filtered water. These gravity filtrations systems used in homes vary in sizes, defined by the capacity of the two chambers. One such gravity filtration system commonly used in homes is the carafe type of filter with the top container having a capacity less than 3 liters. The gravity pressure of the untreated water is sufficient to force the water through a limited amount of activated carbon granules and ion exchange resins.
In the prior art, replaceable filter cartridges for household use have been taught and claimed. U.S. Pat. No. 4,212,743 teaches and claims a filter cartridge of particles of activated charcoal and carbon or other suitable absorbent material wherein the cartridge is contained within a housing. Water is filtered by passing it through the tubular wall of the cartridge from the space between the cartridge and the housing toward the outlet or the inside of the tubular cartridge. The filter cartridge is generally cup-shaped. The filter cartridge structure provides a long flow path of approximately seven inches for water traveling from the inlet to the outlet to provide effective odor and taste filtering of the water with a long contact time.
U.S. Pat. No. 3,972,694 teaches and claims a filter tube comprising a plurality of randomly disposed glass fibers having intensities between to define the porosity of the filter. The glass fibers are bonded at the junctions of the fiber cross-overs with a hardened silicone resin bonding agent, the fibers interrelated to form a semi-rigid mass of desired porosity to incorporate an outer absorbent activated carbon-filled filter sleeve. The bonding agent typically may be phenal-formaldahyde or epoxy resins or other thermosetting-type resins. However, the bonding agent can impart hydrophobicity to the filter and restrict the scope of the filter applications in that organic bonding agents can have a color, which darkens with sunlight and use.
U.S. Pat. No. 5,225,078 teaches and claims a pass-through pitcher filter comprising a compact filter element including a thin annular disk of molded granular activated carbon and a peripheral annular seal element. The seal element allows the filter to be replaceably mounted on the lower end of an upper plastic reservoir, which reservoir is adapted to be supported in the top of a pitcher for receiving filtered water. The plastic reservoir for water to be treated and filter are placed on a pitcher for receiving and dispensing the treated water. Such assemblies rely on gravity flow of the water from the reservoir to the pitcher via the filter. The seal element utilizes a synthetic rubber material and is preferably molded around the carbon filter disk. The filter element is made from a rigid sintered block of activated granular carbon. The carbon block is made from granular activated carbon and a suitable binder, such as polyethylene, compressed and heated to form a molded porous block. In the preferred embodiment, a carbon block has a nominal 20-micron porosity and is approximately ½ inch (13 mm) thick and 4¼ inches (5.5 cm) in diameter. An annular synthetic rubber seal is attached to the periphery of the carbon block. The seal may comprise a neoprene-like material. The seal is formed by injection molding around the carbon block. When the filter element is used initially or after it has remained unused for a period of time, surface tension between water in the reservoir which is to be filtered and the dry porous carbon block may inhibit normal gravity flow of the water through the filter element. To initiate flow, manual pressure is applied to the bellows element of the reservoir to compress air in the reservoir to force water through the carbon block to initiate water flow.
In the prior art, U.S. Pat. No. 6,290,848 teaches and claims a filter cartridge for a gravity-fed water treatment device comprising a hydrophilic porous particulate filter having an interior volume filled with an granular filter media comprising granular activated carbon, an ion exchange resin or a combination thereof. The porous particulate filter is microporous, comprises pleated sheet filter media, and is arranged to establish with a pressure of about 0.5 lb./in2 a flow rate of water by gravity through the filter cartridge. The preferred form of carbon of use is granular activated carbon. The preferred granular media for use in the filter cartridge is a mixture of a weak-acid cation exchange resin and granular activated carbon. Such a device has a low flow rate, which is not practical for a gravity fed water treatment device. To overcome this limitation, the porous particulate filter contains hydrophilic material. The porous glass fiber and hydrophilic binder provides water that has 99.95% of 3-5 micron cyst particles removed. However, such a device does not typically remove volatile organic chemicals as not being capable of doing so without specified treating chemicals or materials
Other prior art patents disclose procedures and structures relating to portable water filters. U.S. Pat. No. 4,151,092 teaches use of a manual pump to force liquid from a first container through a filter to treat the liquid at a suitable rate. U.S. Pat. Nos. 4,306,971 and 4,969,996 disclose a cup-shaped insert for a granular purifying agent to purify water. U.S. Pat. No. 5,268,093 teaches use of a plunger to force unfiltered water through a filter.
Accordingly, it is an object of this invention to provide a water filter having improved fluid flow as compared with prior art filters.
It is another object of this invention to provide a fluid filter having a removable filter medium adapted for field removal, cleaning, and replacement.
It is another object of this invention to provide a filter capable of removing harmful chemicals known as disinfectant byproducts (DBP) and volatile organic chemicals (VOC) and protozoan cysts.
It is another object of this invention to provide a fluid filler having improved structural characteristics by use of ultra high molecular weight polyethylene as the structural material.